<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style>
		div {
			color: red;
		}
		p {
			color: green;
		}
		/*因为demo 没有选p标签，所以 继承的权重为 0*/
		.demo {
			color: blue;
		}
		#test {
			color: pink;
		}
	</style>
</head>
<body>
	<div class="demo" id="test">
		<p>继承的权重为 0</p>
	</div>
</body>
</html>